EP2511697A1 - Device for detecting sulfur component - Google Patents
Device for detecting sulfur component Download PDFInfo
- Publication number
- EP2511697A1 EP2511697A1 EP09852083A EP09852083A EP2511697A1 EP 2511697 A1 EP2511697 A1 EP 2511697A1 EP 09852083 A EP09852083 A EP 09852083A EP 09852083 A EP09852083 A EP 09852083A EP 2511697 A1 EP2511697 A1 EP 2511697A1
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- EP
- European Patent Office
- Prior art keywords
- stored
- amount
- storage portion
- detector
- detecting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 239000011593 sulfur Substances 0.000 title claims abstract description 50
- 229910052717 sulfur Inorganic materials 0.000 title claims abstract description 50
- 230000007423 decrease Effects 0.000 claims abstract description 7
- 239000007789 gas Substances 0.000 claims description 45
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 21
- 229910052760 oxygen Inorganic materials 0.000 claims description 21
- 239000001301 oxygen Substances 0.000 claims description 21
- 229910002651 NO3 Inorganic materials 0.000 claims description 12
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 12
- 239000000446 fuel Substances 0.000 description 19
- 239000003054 catalyst Substances 0.000 description 17
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 230000008929 regeneration Effects 0.000 description 6
- 238000011069 regeneration method Methods 0.000 description 6
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000011232 storage material Substances 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 239000011575 calcium Substances 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 229910052792 caesium Inorganic materials 0.000 description 1
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- -1 sulfuric acid ion Chemical class 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
- G01N33/0042—SO2 or SO3
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
- F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
- F02D41/0275—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a NOx trap or adsorbent
- F02D41/028—Desulfurisation of NOx traps or adsorbent
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
- G01N25/48—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on solution, sorption, or a chemical reaction not involving combustion or catalytic oxidation
- G01N25/4873—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on solution, sorption, or a chemical reaction not involving combustion or catalytic oxidation for a flowing, e.g. gas sample
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/08—Exhaust gas treatment apparatus parameters
- F02D2200/0818—SOx storage amount, e.g. for SOx trap or NOx trap
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Definitions
- the present invention relates to a detector for detecting sulfur components.
- a SO x concentration sensor for detecting a SO x concentration in the exhaust gas is known.
- a usual SO x concentration sensor measures an electromotive force produced when SO x changes into sulfuric acid ion within solid electrolyte, to detect a SO x concentration in the exhaust gas.
- a proposed detector for detecting sulfur components cannot detect an instantaneous SO x concentration but can detect an integrated amount of SO x passing through the exhaust passage during a given period (for example, refer to Japanese Unexamined Patent Publication No. 2008-175623 ).
- the detector for detecting sulfur components comprises a SO x storage portion for storing SO x contained in the exhaust gas, measures a property such as an electric resistance, an volume, a heat capacity or the like of the SO x storage portion changing with the increase of an amount of SO x stored in the SO x storage portion and detects an integrated amount of SO x passing through the exhaust passage during a given period on the basis of the measured property.
- the above-mentioned detector may be not able to accurately detect an integrated amount of SO x passing through the exhaust passage during a given period.
- an object of the present invention is to provide a detector for detecting sulfur components, which can accurately measure an integrated amount of SO x passing through the exhaust passage in a given period or a value on the basis of the integrated amount.
- a detector for detecting sulfur components as set forth in claim 1 of the present invention comprising a storage portion for storing SO x and NO x in the exhaust gas passing through an exhaust passage, in which the more an amount of stored SO x increases, the more an amount of NO x that can be stored decreases, estimating the amount of stored SO x on the basis of an amount of NO x stored in the storage portion, and detecting an integrated amount of SO x passing through the exhaust passage during a given period or an value on the basis of the integrated amount, characterized in that the estimating of the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount is prohibited when a current amount of NO x that can be stored is not stored in the storage portion.
- a detector for detecting sulfur components as set forth in claim 2 of the present invention is provided as the detector for detecting sulfur components as set forth in claim 1 characterized in that the estimating of the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount is prohibited when a temperature of the storage portion is out of a set temperature range.
- a detector for detecting sulfur components as set forth in claim 3 of the present invention is provided as the detector for detecting sulfur components as set forth in claim 2 characterized in that the set temperature range includes a temperature at which a current amount of NO x that can be stored in the storage portion is maximized.
- a detector for detecting sulfur components as set forth in claim 4 of the present invention is provided as the detector for detecting sulfur components as set forth in claim 1 characterized in that after all NO x and SO x stored in the storage portion are released, an amount of NO x stored in the storage portion during a set period is detected by releasing all the amount of stored NO x , when the set period is gradually lengthened, each amount of NO x stored in the storage portion during each set period is detected, a maximum value of the detected amounts of stored NO x is set to a current amount of NO x that can be stored in the storage portion when SOx is not stored.
- a detector for detecting sulfur components as set forth in claim 5 of the present invention is provided as the detector for detecting sulfur components as set forth in any one of claims 1-4 characterized in that the storage portion stores NO x in exhaust gas as nitrate and oxygen is supplied in the vicinity of the storage portion.
- the detector for detecting sulfur components as set forth in claim 1 of the present invention, comprises a storage portion for storing SO x and NO x in the exhaust gas passing through an exhaust passage, in which the more an amount of stored SO x increases, the more an amount of NO x that can be stored decreases, so that an amount of stored SO x can be estimated on the basis of an amount of NO x stored in the storage portion, and an integrated amount of SO x passing through the exhaust passage during a given period or an value on the basis of the integrated amount can be detected on the basis the amount of stored SO x in the storage portion because a given rate of an amount of SO x passing through the exhaust passage is stored in the storage portion of the detector.
- the estimating of the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount a current amount of NO x that can be stored must be stored in the storage portion. If the amount of stored SO x was estimated on the basis of the amount of stored NO x when the current amount of NO x that can be stored was not stored in the storage portion, the estimated amount of stored SO x will become more than the actual amount. Accordingly, the estimating of the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount is prohibited when a current amount of NO x that can be stored is not stored in the storage portion.
- the detector for detecting sulfur components as set forth in claim 2 of the present invention in the detector for detecting sulfur components as set forth in claim 1, the estimating of the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount is prohibited when a temperature of the storage portion is out of a set temperature range.
- a current amount of NO x that can be stored in the storage portion changes in accordance with a temperature of the storage portion, and if the amount of stored SO x was estimated on the basis of the amount stored NO x when the temperature of the storage portion became out of the set temperature range and the current amount of NO x that can be stored decreased (or increased) by the change of the temperature, the estimated amount of stored SO x will become more (or less) than the actual amount.
- the set temperature range includes a temperature at which a current amount of NO x that can be stored in the storage portion is maximized. Therefore, when the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount is estimated, the amount of stored NO x becomes relatively large so that the amount of stored NO x can be easily measured.
- the detector for detecting sulfur components as set forth in claim 4 of the present invention in the detector for detecting sulfur components as set forth in claim 1, after all NO x and SO x stored in the storage portion are released, an amount of NO x stored in the storage portion during a set period is detected by releasing all the amount of stored NO x , when the set period is gradually lengthened, each amount of NO x stored in the storage portion during each set period is detected, a maximum value of the detected amounts of stored NO x is set to a current amount of NO x that can be stored in the storage portion when SO x is not stored.
- the current amount of NO x that can be stored in the storage portion when SO x is not stored changes in accordance with deterioration of the storage portion.
- the current amount of NO x that can be stored in the storage portion when SO x is not stored can be reliably updated without SO x stored in the storage portion as the storage portion is not exposed in the exhaust gas for a long time. Therefore, when the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount is estimated, the amount of stored SO x can be estimated relative accurately on the basis of the amount of NO x stored in the storage portion.
- the storage portion stores NO x in exhaust gas as nitrate so that when oxygen is supplied in the vicinity of the storage portion, NO in the exhaust gas is oxidized to NO 2 by the supplied oxygen so as to be easily stored in the storage portion as nitrate.
- Fig. 1 is a schematic view showing an engine exhaust system in which a detector for detecting sulfur components according to the present invention is arranged.
- reference numeral 1 is an exhaust passage of an internal combustion engine.
- the engine performs lean combustion such as in a diesel engine or a direct fuel injection-type spark-ignition engine.
- the exhaust gas of such an engine includes a relatively large amount of NO x so that a NO x catalyst device 2 for purifying NO x is arranged in the exhaust passage 1.
- the NO x catalyst device 2 carries a NO x storage material and a noble metal catalyst such as platinum Pt.
- the NO x storage material is at least one element selected from for example potassium K, sodium Na, lithium Li, cesium Cs, or another alkali metal, barium Ba, calcium Ca, or another alkali earth metal, and lanthanum La, yttrium Y, or another rare earth.
- the NO x catalyst device 2 satisfactorily stores NO x in the exhaust gas so as to absorb NO x as nitrate or so as to adsorb NO x as NO 2 when the air-fuel ratio of the exhaust gas is lean, that is, when the oxygen concentration of the exhaust gas is high.
- the NO x catalyst device cannot store NO x without limitation. Accordingly, before the NO x catalyst device can not almost store further NO x because an amount of NO x stored in the NO x catalyst device almost reaches the largest amount of NO x that can be stored therein, the air-fuel ratio of the exhaust gas is changed to a stoichiometric air-fuel ratio or a rich air-fuel ratio as the regeneration treatment, namely, the concentration of oxygen of the exhaust gas is lowered. Therefore, the stored NO x is separated, namely, the absorbed NO x is released or the adsorbed NO 2 is disconnected, and thereafter the separated NO x is reduced and purified to N 2 by reducing materials in the exhaust gas.
- a S trap device 3 which can store SO x in the exhaust gas is arranged upstream of the NO x catalyst device 2 in the exhaust passage 1 to restrain the sulfur contamination of the NO x catalyst device 2.
- the detector for detecting sulfur components 4 according to the present invention is arranged, for example, between the S trap device 3 and the NO x catalyst device 2, and detects an integrated amount of SO x passing through the S trap device 3. When the integrated amount of SO x reaches a set value, it can be determined that it is a time to exchange the S trap device 3 for a new one.
- Fig. 2 is a schematic sectional view showing an embodiment of the detector for detecting sulfur components 4 according to the present invention.
- reference numeral 10 is an outer wall of the exhaust passage 1.
- Reference numeral 41 is a base plate of the detector for detecting sulfur components 4.
- a temperature sensor 42 such as a thermocouple is arranged on one side (preferably exhaust gas upstream side) of the base plate 41.
- an electric heater 43 is arranged on the other side of the base plate 41.
- Reference numeral 44 is a storage portion for NO x and SO x arranged so as to cover the temperature sensitive portion of the temperature sensor 42.
- Reference numeral 45 is a cylindrical case which surrounds the detector for detecting sulfur components 4 having the above-construction and goes through the outer wall 10 of the exhaust passage 1.
- Reference numeral 46 is an oxygen pump for supplying oxygen (for example, oxygen in the atmosphere) in the vicinity of the storage portion 44 within the case 45, and the oxygen pump is arranged around the unit of the temperature sensor 42, the base plate 41, and the electric heater 43 to separate the space around the storage portion 44 within the case 45 from the atmosphere chamber.
- the oxygen pump 46 is made from zirconia or the like. In contrast with a zirconia oxygen sensor, the oxygen pump can make oxygen in the atmosphere move to the vicinity of the storage portion 44 within the case 45 by impressing voltage.
- the storage portion 44 stores NO x and SO x in the exhaust gas and can be formed to apply the above-mentioned NO x storage material and a noble metal catalyst such as platinum Pt on the temperature sensitive portion of the temperature sensor 42.
- the storage portion 44 constructed like this absorbs NO x in the exhaust gas as nitrate and absorbs SO x in the exhaust gas as sulfate instead of NO x .
- the storage portion 44 has an amount of NO x that can be stored (B) when SO x is not stored (or an amount of NO x and SO x that can be stored). Sulfate is more stable than nitrate so that an amount of NO x that can be stored (B) when SO x is not stored is a standard and the more an amount of stored SO x increases, the more a current amount of NO x that can be stored decrease.
- an integrated amount of SO x passing through the exhaust passage 1 at the position of the detector for detecting sulfur components during a given period can be detected, or an average value of each SO x concentration in the exhaust gas passing through the exhaust passage 1 at the position of the detector for detecting sulfur components during the given period or an average value of each amount of SO x passing through the exhaust passage 1 at the position of the detector for detecting sulfur components during the given period can be detected as a value on the basis of the integrated amount of SO x .
- Fig. 3 is a flow chart for detecting an integrated amount of SO x or a value on the basis of the integrated amount by the detector for detecting sulfur components 4 and is carried out in an electronic control unit (not shown).
- step 101 it is determined if it is a time to detect an integrated amount of SO x .
- the routine is finished.
- the result at step 101 is positive and the routine goes to step 102.
- step 102 it is determined if an elapsed time (t) which is explained later in detail reaches a set time (t'). This determination is repeated until the result at step 102 is positive.
- a temperature (T) of the storage portion 44 of the detector for detecting sulfur components 4 is measured by the temperature sensor 42 and it is determined if the measured temperature (T) is within a set temperature range from a first temperature (T1) (for example, 350-380 degrees C) to a second temperature (T2) (for example, 400-430 degrees C). This determination is repeated until the result at step 103 is positive.
- T1 for example, 350-380 degrees C
- T2 for example, 400-430 degrees C
- the electric heater 43 may be operated such that the result at step 103 is positive. If necessary, the electric heater 43 may be operated such that the temperature (T) of the storage portion 44 is always maintained within the set temperature range (from T1 to T2).
- a given rate of an amount of SO x passing through the exhaust passage 1 at the position of the detector for detecting sulfur components 4 is stored in the storage portion 44 of the detector 4. Therefore, at step 106, an integrated amount of SO x passing through the exhaust passage 1 at the position of the detector 4 during the given period is detected on the basis of the current amount of stored SO x .
- the elapsed time (t) is reset to 0 and the routine is finished.
- the amount of NO x stored in the storage portion 44 (A) detected at step 104 must be equal to the current amount of NO x that can be stored which is decreased by the stored SO x . Namely, when the amount of SO x stored in the storage portion 44 (B-A) at step 105 is estimated, it is required that the current amount of NO x that can be stored is stored in the storage portion 44. If the amount of stored SO x is estimated on the basis of the amount of stored NO x when the current amount of NO x that can be stored is not stored in the storage portion, the estimated amount of stored SO x becomes more than an actual amount.
- the elapsed time (t) is reset to 0 when the engine is started initially or is reset to 0 at step 107 of the present flow chart.
- the elapsed time (t) is reset to 0 when all amount of NO x is released from storage portion 44.
- the air-fuel ratio of the exhaust gas is changed to rich and all amount of NO x is released from the storage portion 44 so that the elapsed time (t) is reset to 0 when the regeneration treatment is finished.
- to reset the integrated amount of SO x all amount of stored SO x is released from the storage portion 44. In this case, all amount of NO x is also released from the storage portion 44 so that the elapsed time (t) is reset to 0.
- Fig. 4 shows the amount of NO x that can be stored (B) in the storage portion 44 formed from the NO x storage material (Ba) when SO x is not stored.
- the amount of NO x that can be stored in each amount of stored SO x is maximum when the temperature of the storage portion 44 is T1 (350-380 degrees C) and is maintained relative high when the temperature of the storage portion 44 is between T1 and T2 (400-430 degrees C).
- the temperature (T) of the storage portion 44 when the current amount of NO x stored in the storage portion 44 (A) is detected corresponds with a set temperature of the storage portion 44 at which the amount of NO x that can be stored (B) when SO x is not stored is determined as the standard. At least, when the temperature (T) of the storage portion 44 is out of the set temperature range including this set temperature, it is preferable to prohibit the estimation of the amount of stored SO x for detecting the integrated amount of SO x .
- the amount of stored SO x is estimated on the basis of the amount of stored NO x , the estimated amount of stored SO x becomes more than the actual amount.
- the result at step 103 is negative and the processes after step 104 including the estimating of the amount of stored SO x for detecting the integrated amount of SO x are prohibited (are not carried out).
- the set temperature of the storage portion 44 at which the amount of NO x that can be stored (B) when SO x is not stored is determined as the standard is preferably for example 350 degrees C at which the amount of NO x that can be stored (B) becomes maximum.
- the set temperature range at step 103 includes preferably the temperature of the storage portion (for example 350 degrees C) at which the amount of NO x that can be stored (B) becomes maximum.
- the storage portion 44 of the detector for detecting sulfur components 4 stores NO x in the exhaust gas as nitrate, like the present embodiment, if oxygen is supplied in the vicinity of the storage portion 44, NO in the exhaust gas is oxidized to NO 2 by the supplied oxygen and is easily stored in the storage portion 44 as nitrate.
- the oxygen concentration in the exhaust gas flowing into the case 45 becomes relatively low. Therefore, except during the air-fuel ratio of the exhaust gas is intentionally made rich in the regeneration treatment of NO x catalyst device 2, the process for releasing NO x from the storage portion 44 mentioned above, or the like, the oxygen pump 46 is preferably operated to supply oxygen in the vicinity of the storage portion 44 such that NO in the exhaust gas is easily stored in the storage portion 44.
- the air-fuel ratio of the exhaust gas in the vicinity of the storage portion 44 is preferably made 40 and over.
- the current amount of NO x that can be stored in the storage portion 44 on the basis of each amount of stored SO x is gradually decreased according to the deterioration thereof. Therefore, to accurately estimate the amount of stored SO x for detecting the integrated amount of SO x or the value on the basis of the integrated amount, the amount of NO x that can be stored (B) when SO x is not stored determined as the standard must be updated to a current value.
- the current amount of NO x that can be stored in the storage portion decreases with the deterioration, if the amount of store SO x is estimated on the basis of the original standard, the estimated amount of stored SO x becomes more than the actual amount.
- Fig. 5 is a flow chart for updating the amount of NO x that can be stored when SO x is not stored used as the standard and is carried out in the electronic control unit.
- the amount of SO x stored in the storage portion 44 is required to be reset to 0.
- the air-fuel ratio of the exhaust gas must be not only made rich but the temperature of the storage portion 44 must be also made high (for example, 650 degrees C). Therefore, reduction materials in the exhaust gas may be oxidized by using of the noble metal catalyst on the storage portion 44 to raise the temperature of the storage portion 44 or the electric heater 43 may raise the temperature of the storage portion 44.
- step 201 When the result at step 201 is negative, the routine is finished.
- step 202 the elapsed time (t) is reset to 0 as explained in the flow chart in Fig. 3 .
- step 203 it is determined if the elapsed time (t) reaches a set period (ts). The determination is repeated until the result is positive.
- step 204 an amount of NO x stored in the storage portion 44 (A) during the set period (ts) is detected to make the air-fuel ratio of the exhaust gas rich as mentioned above.
- step 205 it is determined if the amount of stored NO x detected at this time (A) is equal to about the amount of stored NO x detected at the last time (A'). At first, the amount of stored NO x detected at the last time (A') is 0 and thus the result at step 205 is negative. Therefore, the routine goes to step 206.
- step 206 the amount of stored NO x detected at this time (A) is made the amount of stored NO x detected at the last time (A').
- step 207 the set period (ts) mentioned above is increased by (a) and the routine returns step 202.
- the set period (ts) is gradually lengthened and thus the amount of NO x stored in the storage portion 44 during the set period (ts) is gradually increased.
- the current amount of NO x that can be stored in the storage portion 44 is stored. Therefore, at next time, the amount of stored NO x detected at this time (A) is equal to about the amount of stored NO x detected at the last time (A'), the result at step 205 is positive, and the routine goes to step 208.
- the current amount of NO x that can be stored in the storage portion 44 can be detected accurately at a short time.
- the amount of NO x stored in the storage portion 44 (A) detected in this way is the amount of NO x that can be stored when the storage portion 44 is exposed only during a short period (a few minutes or a few ten minutes) after all NO x and SO x stored in the storage portion 44 have been released and becomes the current amount of NO x that can be stored in the storage portion 44 (B) when SO x is not stored because SO x is not almost stored in the storage portion 44 during such a short period. Accordingly, at step 208, the amount of stored NO x detected at this time (A) is made the current amount of NO x that can be stored (B) in the storage portion 44 when SO x is not stored. Next, at step 209, the amount of stored NO x detected at the last time (A') is reset to 0 and the routine is finished.
- the current amount of NO x that can be stored in the storage portion 44 (B) when SO x is not stored is updated as the standard, and can be used in the estimation of the amount of SO x stored in the storage portion 44 (B-A) at step 105 of the flow chart in Fig. 3 .
- the elapsed time (t) for storing NO x in the storage portion 44 can be changed to a running distance.
- the air-fuel ratio of the exhaust gas is made rich to detect the amount of NO x stored in the storage portion 44 (A).
- This does not limit to the present invention. For example, even if the oxygen concentration is not dropped, NO x stored in the storage portion 44 is released when the temperature of the storage portion becomes about 500 degrees C. Accordingly, with utilizing this, the electric heater 43 heats the storage portion 44 and the amount of NO x stored in the storage portion 44 (A) may be detected on the basis of a quantity of heat used to release all amount of NO x from the storage portion 44.
- the air-fuel ratio of the exhaust gas When the air-fuel ratio of the exhaust gas is made rich in the regeneration treatment of the NO x catalyst device 2 and the detection of the amount of NO x stored in the storage portion 44, the air-fuel ratio of combustion in the engine may be made rich, additional fuel may be supplied into cylinder in exhaust stroke or expansion stroke, or fuel may be supplied to the exhaust gas in the exhaust passage 1.
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Abstract
Description
- The present invention relates to a detector for detecting sulfur components.
- A SOx concentration sensor for detecting a SOx concentration in the exhaust gas is known. A usual SOx concentration sensor measures an electromotive force produced when SOx changes into sulfuric acid ion within solid electrolyte, to detect a SOx concentration in the exhaust gas. However, it is difficult for such a SOx concentration sensor for detecting an instantaneous SOx concentration to detect an accurate SOx concentration when the SOx concentration in the exhaust gas is low.
- A proposed detector for detecting sulfur components cannot detect an instantaneous SOx concentration but can detect an integrated amount of SOx passing through the exhaust passage during a given period (for example, refer to Japanese Unexamined Patent Publication No.
2008-175623 - The detector for detecting sulfur components comprises a SOx storage portion for storing SOx contained in the exhaust gas, measures a property such as an electric resistance, an volume, a heat capacity or the like of the SOx storage portion changing with the increase of an amount of SOx stored in the SOx storage portion and detects an integrated amount of SOx passing through the exhaust passage during a given period on the basis of the measured property.
- Because it is difficult to accurately measure a change of a property such as an electric resistance, a volume, a heat capacity or the like, the above-mentioned detector may be not able to accurately detect an integrated amount of SOx passing through the exhaust passage during a given period.
- Accordingly, an object of the present invention is to provide a detector for detecting sulfur components, which can accurately measure an integrated amount of SOx passing through the exhaust passage in a given period or a value on the basis of the integrated amount.
- A detector for detecting sulfur components as set forth in
claim 1 of the present invention, comprising a storage portion for storing SOx and NOx in the exhaust gas passing through an exhaust passage, in which the more an amount of stored SOx increases, the more an amount of NOx that can be stored decreases, estimating the amount of stored SOx on the basis of an amount of NOx stored in the storage portion, and detecting an integrated amount of SOx passing through the exhaust passage during a given period or an value on the basis of the integrated amount, characterized in that the estimating of the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount is prohibited when a current amount of NOx that can be stored is not stored in the storage portion. - A detector for detecting sulfur components as set forth in
claim 2 of the present invention is provided as the detector for detecting sulfur components as set forth inclaim 1 characterized in that the estimating of the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount is prohibited when a temperature of the storage portion is out of a set temperature range. - A detector for detecting sulfur components as set forth in
claim 3 of the present invention is provided as the detector for detecting sulfur components as set forth inclaim 2 characterized in that the set temperature range includes a temperature at which a current amount of NOx that can be stored in the storage portion is maximized. - A detector for detecting sulfur components as set forth in
claim 4 of the present invention is provided as the detector for detecting sulfur components as set forth inclaim 1 characterized in that after all NOx and SOx stored in the storage portion are released, an amount of NOx stored in the storage portion during a set period is detected by releasing all the amount of stored NOx, when the set period is gradually lengthened, each amount of NOx stored in the storage portion during each set period is detected, a maximum value of the detected amounts of stored NOx is set to a current amount of NOx that can be stored in the storage portion when SOx is not stored. - A detector for detecting sulfur components as set forth in claim 5 of the present invention is provided as the detector for detecting sulfur components as set forth in any one of claims 1-4 characterized in that the storage portion stores NOx in exhaust gas as nitrate and oxygen is supplied in the vicinity of the storage portion.
- According to the detector for detecting sulfur components as set forth in
claim 1 of the present invention, the detector comprises a storage portion for storing SOx and NOx in the exhaust gas passing through an exhaust passage, in which the more an amount of stored SOx increases, the more an amount of NOx that can be stored decreases, so that an amount of stored SOx can be estimated on the basis of an amount of NOx stored in the storage portion, and an integrated amount of SOx passing through the exhaust passage during a given period or an value on the basis of the integrated amount can be detected on the basis the amount of stored SOx in the storage portion because a given rate of an amount of SOx passing through the exhaust passage is stored in the storage portion of the detector. In the estimating of the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount, a current amount of NOx that can be stored must be stored in the storage portion. If the amount of stored SOx was estimated on the basis of the amount of stored NOx when the current amount of NOx that can be stored was not stored in the storage portion, the estimated amount of stored SOx will become more than the actual amount. Accordingly, the estimating of the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount is prohibited when a current amount of NOx that can be stored is not stored in the storage portion. - According to the detector for detecting sulfur components as set forth in
claim 2 of the present invention, in the detector for detecting sulfur components as set forth inclaim 1, the estimating of the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount is prohibited when a temperature of the storage portion is out of a set temperature range. Because a current amount of NOx that can be stored in the storage portion changes in accordance with a temperature of the storage portion, and if the amount of stored SOx was estimated on the basis of the amount stored NOx when the temperature of the storage portion became out of the set temperature range and the current amount of NOx that can be stored decreased (or increased) by the change of the temperature, the estimated amount of stored SOx will become more (or less) than the actual amount. - According to the detector for detecting sulfur components as set forth in
claim 3 of the present invention, in the detector for detecting sulfur components as set forth inclaim 2, the set temperature range includes a temperature at which a current amount of NOx that can be stored in the storage portion is maximized. Therefore, when the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount is estimated, the amount of stored NOx becomes relatively large so that the amount of stored NOx can be easily measured. - According to the detector for detecting sulfur components as set forth in
claim 4 of the present invention, in the detector for detecting sulfur components as set forth inclaim 1, after all NOx and SOx stored in the storage portion are released, an amount of NOx stored in the storage portion during a set period is detected by releasing all the amount of stored NOx, when the set period is gradually lengthened, each amount of NOx stored in the storage portion during each set period is detected, a maximum value of the detected amounts of stored NOx is set to a current amount of NOx that can be stored in the storage portion when SOx is not stored. The current amount of NOx that can be stored in the storage portion when SOx is not stored, changes in accordance with deterioration of the storage portion. Thus, when all NOx and SOx stored in the storage portion are released, the current amount of NOx that can be stored in the storage portion when SOx is not stored, can be reliably updated without SOx stored in the storage portion as the storage portion is not exposed in the exhaust gas for a long time. Therefore, when the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount is estimated, the amount of stored SOx can be estimated relative accurately on the basis of the amount of NOx stored in the storage portion. - According to the detector for detecting sulfur components as set forth in claim 5 of the present invention, in the detector for detecting sulfur components as set forth in any one of claims 1-4, the storage portion stores NOx in exhaust gas as nitrate so that when oxygen is supplied in the vicinity of the storage portion, NO in the exhaust gas is oxidized to NO2 by the supplied oxygen so as to be easily stored in the storage portion as nitrate.
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Fig. 1 is a schematic view showing an engine exhaust system in which a detector for detecting sulfur components according to the present invention is arranged. -
Fig. 2 is a schematic sectional view showing an embodiment of the detector for detecting sulfur components according to the present invention. -
Fig. 3 is a flow chart for detecting an integrated amount of SOx or a value on the basis of the integrated amount by using of the detector for detecting sulfur components according to the present invention. -
Fig. 4 is a graph showing a relationship between a temperature of the storage portion of the detector for detecting sulfur components according to the present invention and an amount of NOx that can be stored in the storage portion when SOx is not stored. -
Fig. 5 is a flow chart for updating the amount of NOx that can be stored in the storage portion when SOx is not stored of the detector for detecting sulfur components according to the present invention. -
Fig. 1 is a schematic view showing an engine exhaust system in which a detector for detecting sulfur components according to the present invention is arranged. InFig. 1 ,reference numeral 1 is an exhaust passage of an internal combustion engine. The engine performs lean combustion such as in a diesel engine or a direct fuel injection-type spark-ignition engine. The exhaust gas of such an engine includes a relatively large amount of NOx so that a NOxcatalyst device 2 for purifying NOx is arranged in theexhaust passage 1. - The NOx
catalyst device 2 carries a NOx storage material and a noble metal catalyst such as platinum Pt. The NOx storage material is at least one element selected from for example potassium K, sodium Na, lithium Li, cesium Cs, or another alkali metal, barium Ba, calcium Ca, or another alkali earth metal, and lanthanum La, yttrium Y, or another rare earth. - The NOx
catalyst device 2 satisfactorily stores NOx in the exhaust gas so as to absorb NOx as nitrate or so as to adsorb NOx as NO2 when the air-fuel ratio of the exhaust gas is lean, that is, when the oxygen concentration of the exhaust gas is high. However, the NOx catalyst device cannot store NOx without limitation. Accordingly, before the NOx catalyst device can not almost store further NOx because an amount of NOx stored in the NOx catalyst device almost reaches the largest amount of NOx that can be stored therein, the air-fuel ratio of the exhaust gas is changed to a stoichiometric air-fuel ratio or a rich air-fuel ratio as the regeneration treatment, namely, the concentration of oxygen of the exhaust gas is lowered. Therefore, the stored NOx is separated, namely, the absorbed NOx is released or the adsorbed NO2 is disconnected, and thereafter the separated NOx is reduced and purified to N2 by reducing materials in the exhaust gas. - Once the NOx
catalyst device 2 stores SOx in the exhaust gas as sulfate, sulfate is more stable than nitrate so that the stored SOx cannot be released by the regeneration treatment and an amount of NOx that can be stored drops (sulfur contamination). Therefore, aS trap device 3 which can store SOx in the exhaust gas is arranged upstream of the NOxcatalyst device 2 in theexhaust passage 1 to restrain the sulfur contamination of the NOxcatalyst device 2. - The detector for detecting
sulfur components 4 according to the present invention is arranged, for example, between theS trap device 3 and the NOxcatalyst device 2, and detects an integrated amount of SOx passing through theS trap device 3. When the integrated amount of SOx reaches a set value, it can be determined that it is a time to exchange theS trap device 3 for a new one. -
Fig. 2 is a schematic sectional view showing an embodiment of the detector for detectingsulfur components 4 according to the present invention. InFig. 2 ,reference numeral 10 is an outer wall of theexhaust passage 1.Reference numeral 41 is a base plate of the detector for detectingsulfur components 4. Atemperature sensor 42 such as a thermocouple is arranged on one side (preferably exhaust gas upstream side) of thebase plate 41. On the other hand, anelectric heater 43 is arranged on the other side of thebase plate 41. Reference numeral 44 is a storage portion for NOx and SOx arranged so as to cover the temperature sensitive portion of thetemperature sensor 42.Reference numeral 45 is a cylindrical case which surrounds the detector for detectingsulfur components 4 having the above-construction and goes through theouter wall 10 of theexhaust passage 1. - A plurality of
openings 45a is formed on thecase 45. The exhaust gas passing through theexhaust passage 1 flows into thecase 45 via theopenings 45a.Reference numeral 46 is an oxygen pump for supplying oxygen (for example, oxygen in the atmosphere) in the vicinity of the storage portion 44 within thecase 45, and the oxygen pump is arranged around the unit of thetemperature sensor 42, thebase plate 41, and theelectric heater 43 to separate the space around the storage portion 44 within thecase 45 from the atmosphere chamber. Theoxygen pump 46 is made from zirconia or the like. In contrast with a zirconia oxygen sensor, the oxygen pump can make oxygen in the atmosphere move to the vicinity of the storage portion 44 within thecase 45 by impressing voltage. - The storage portion 44 stores NOx and SOx in the exhaust gas and can be formed to apply the above-mentioned NOx storage material and a noble metal catalyst such as platinum Pt on the temperature sensitive portion of the
temperature sensor 42. - As mentioned above, the storage portion 44 constructed like this absorbs NOx in the exhaust gas as nitrate and absorbs SOx in the exhaust gas as sulfate instead of NOx. The storage portion 44 has an amount of NOx that can be stored (B) when SOx is not stored (or an amount of NOx and SOx that can be stored). Sulfate is more stable than nitrate so that an amount of NOx that can be stored (B) when SOx is not stored is a standard and the more an amount of stored SOx increases, the more a current amount of NOx that can be stored decrease.
- On the basis of this relationship, an integrated amount of SOx passing through the
exhaust passage 1 at the position of the detector for detecting sulfur components during a given period can be detected, or an average value of each SOx concentration in the exhaust gas passing through theexhaust passage 1 at the position of the detector for detecting sulfur components during the given period or an average value of each amount of SOx passing through theexhaust passage 1 at the position of the detector for detecting sulfur components during the given period can be detected as a value on the basis of the integrated amount of SOx. -
Fig. 3 is a flow chart for detecting an integrated amount of SOx or a value on the basis of the integrated amount by the detector for detectingsulfur components 4 and is carried out in an electronic control unit (not shown). First, atstep 101, it is determined if it is a time to detect an integrated amount of SOx. When the result atstep 101 is negative, the routine is finished. On the other hand, when it is necessary to detect an integrated amount of SOx regularly or irregularly, the result atstep 101 is positive and the routine goes to step 102. - At
step 102, it is determined if an elapsed time (t) which is explained later in detail reaches a set time (t'). This determination is repeated until the result atstep 102 is positive. When the result atstep 102 is positive, atstep 103, a temperature (T) of the storage portion 44 of the detector for detectingsulfur components 4 is measured by thetemperature sensor 42 and it is determined if the measured temperature (T) is within a set temperature range from a first temperature (T1) (for example, 350-380 degrees C) to a second temperature (T2) (for example, 400-430 degrees C). This determination is repeated until the result atstep 103 is positive. In case that a temperature of the exhaust gas is low, when the result atstep 101 is negative, for example, theelectric heater 43 may be operated such that the result atstep 103 is positive. If necessary, theelectric heater 43 may be operated such that the temperature (T) of the storage portion 44 is always maintained within the set temperature range (from T1 to T2). - When the result at
step 103 is positive, an air-fuel ratio of the exhaust gas in the vicinity of the storage portion 44 is made rich to reduce the oxygen concentration in the vicinity of the storage portion 44. Therefore, NOx is released from the storage portion 44 and is reduced as follows.
1/2Ba(NO3)2→1/2BaO+NO+3/4O2-309.6kJ/mol CO+NO→1/2N2+2CO2+373.2kJ/mol
3/2CO+ 3/4O2→3/2CO2+424.5kJ/mol
- Thus, a quantity of heat of about 490kJ is produced for 1mol of NOx. Therefore, an increase value of temperature ΔT (Ta-Tb) between a maximum temperature (Ta) of the storage portion after the air-fuel ratio of the exhaust gas in the vicinity of the storage portion 44 is changed to rich and a temperature (Tb) of the storage portion 44 before the air-fuel ratio of the exhaust gas in the vicinity of the storage portion 44 is changed to rich is measured by the
temperature sensor 42. Atstep 104, an amount of NOx stored in the storage portion 44 (A) (mol) is detected on the basis of this increase value of temperature ΔT. When it is finished to measure the increase value of temperature ΔT, the air-fuel ratio of the exhaust gas is returned to lean of normal engine operations. - When the amount of stored NOx (A) is less than the amount of NOx that can be stored (B) when SOx is not stored, SOx is stored in the storage portion 44 and a current amount of stored SOx (B-A) is estimated at
step 105. - A given rate of an amount of SOx passing through the
exhaust passage 1 at the position of the detector for detectingsulfur components 4 is stored in the storage portion 44 of thedetector 4. Therefore, atstep 106, an integrated amount of SOx passing through theexhaust passage 1 at the position of thedetector 4 during the given period is detected on the basis of the current amount of stored SOx. Next, atstep 107, the elapsed time (t) is reset to 0 and the routine is finished. - In the present flow chart, to estimate accurately the amount of SOx stored in the storage portion 44 (B-A) at
step 105, the amount of NOx stored in the storage portion 44 (A) detected atstep 104 must be equal to the current amount of NOx that can be stored which is decreased by the stored SOx. Namely, when the amount of SOx stored in the storage portion 44 (B-A) atstep 105 is estimated, it is required that the current amount of NOx that can be stored is stored in the storage portion 44. If the amount of stored SOx is estimated on the basis of the amount of stored NOx when the current amount of NOx that can be stored is not stored in the storage portion, the estimated amount of stored SOx becomes more than an actual amount. - In the present flow chart, when the elapsed time (t) does not reach the set time (t'), there is some possibility that the current amount of NOx that can be stored is not stored in the storage portion 44, the result at
step 102 is negative so that the processes afterstep 103 including the estimation of the amount of stored SOx for detecting the integrated amount of SOx are prohibited (are not carried out). - The elapsed time (t) is reset to 0 when the engine is started initially or is reset to 0 at
step 107 of the present flow chart. In addition to these, the elapsed time (t) is reset to 0 when all amount of NOx is released from storage portion 44. For example, in the regeneration treatment of the NOxcatalyst device 2, the air-fuel ratio of the exhaust gas is changed to rich and all amount of NOx is released from the storage portion 44 so that the elapsed time (t) is reset to 0 when the regeneration treatment is finished. On the other hand, to reset the integrated amount of SOx, all amount of stored SOx is released from the storage portion 44. In this case, all amount of NOx is also released from the storage portion 44 so that the elapsed time (t) is reset to 0. - Incidentally, the current amount of NOx that can be stored in the storage portion 44 is changed in accordance with the temperature of the storage portion 44. As an example,
Fig. 4 shows the amount of NOx that can be stored (B) in the storage portion 44 formed from the NOx storage material (Ba) when SOx is not stored. As shown inFig. 4 , the amount of NOx that can be stored in each amount of stored SOx is maximum when the temperature of the storage portion 44 is T1 (350-380 degrees C) and is maintained relative high when the temperature of the storage portion 44 is between T1 and T2 (400-430 degrees C). - Thus, to accurately estimate the amount of stored SOx for detecting the integrated amount of SOx, it is preferable that the temperature (T) of the storage portion 44 when the current amount of NOx stored in the storage portion 44 (A) is detected corresponds with a set temperature of the storage portion 44 at which the amount of NOx that can be stored (B) when SOx is not stored is determined as the standard. At least, when the temperature (T) of the storage portion 44 is out of the set temperature range including this set temperature, it is preferable to prohibit the estimation of the amount of stored SOx for detecting the integrated amount of SOx. For example, when the temperature (T) of the storage portion 44 becomes out of the set temperature range and the amount of NOx that can be stored decreases by the changing of the temperature of the storage portion 44, if the amount of stored SOx is estimated on the basis of the amount of stored NOx, the estimated amount of stored SOx becomes more than the actual amount.
- Accordingly, in the present flow chart, when the temperature of the storage portion 44 is out of the set temperature range, the result at
step 103 is negative and the processes afterstep 104 including the estimating of the amount of stored SOx for detecting the integrated amount of SOx are prohibited (are not carried out). - The set temperature of the storage portion 44 at which the amount of NOx that can be stored (B) when SOx is not stored is determined as the standard is preferably for example 350 degrees C at which the amount of NOx that can be stored (B) becomes maximum. The set temperature range at
step 103 includes preferably the temperature of the storage portion (for example 350 degrees C) at which the amount of NOx that can be stored (B) becomes maximum. Thus, when the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount is estimated, the amount of NOx stored in the storage portion 44 becomes relatively large so that the amount of stored NOx can be easily measured. - Incidentally, in case that the storage portion 44 of the detector for detecting
sulfur components 4 stores NOx in the exhaust gas as nitrate, like the present embodiment, if oxygen is supplied in the vicinity of the storage portion 44, NO in the exhaust gas is oxidized to NO2 by the supplied oxygen and is easily stored in the storage portion 44 as nitrate. - In accordance with the engine operating conditions, the oxygen concentration in the exhaust gas flowing into the
case 45 becomes relatively low. Therefore, except during the air-fuel ratio of the exhaust gas is intentionally made rich in the regeneration treatment of NOxcatalyst device 2, the process for releasing NOx from the storage portion 44 mentioned above, or the like, theoxygen pump 46 is preferably operated to supply oxygen in the vicinity of the storage portion 44 such that NO in the exhaust gas is easily stored in the storage portion 44. Particularly, the air-fuel ratio of the exhaust gas in the vicinity of the storage portion 44 is preferably made 40 and over. - Incidentally, the current amount of NOx that can be stored in the storage portion 44 on the basis of each amount of stored SOx is gradually decreased according to the deterioration thereof. Therefore, to accurately estimate the amount of stored SOx for detecting the integrated amount of SOx or the value on the basis of the integrated amount, the amount of NOx that can be stored (B) when SOx is not stored determined as the standard must be updated to a current value. When the current amount of NOx that can be stored in the storage portion decreases with the deterioration, if the amount of store SOx is estimated on the basis of the original standard, the estimated amount of stored SOx becomes more than the actual amount.
-
Fig. 5 is a flow chart for updating the amount of NOx that can be stored when SOx is not stored used as the standard and is carried out in the electronic control unit. - When it is intended to detect an integrated amount of SOx passing through the
exhaust passage 1 at the position of the detector for detectingsulfur compositions 4 during a new given period or a value on the basis of the integrated amount of SOx, the amount of SOx stored in the storage portion 44 is required to be reset to 0. Atstep 201, in such a case, it is determined if all amount of SOx is released from the storage portion 44. - To release SOx from the storage portion 44, the air-fuel ratio of the exhaust gas must be not only made rich but the temperature of the storage portion 44 must be also made high (for example, 650 degrees C). Therefore, reduction materials in the exhaust gas may be oxidized by using of the noble metal catalyst on the storage portion 44 to raise the temperature of the storage portion 44 or the
electric heater 43 may raise the temperature of the storage portion 44. Thus, when SOx stored in the storage portion 44 as sulfate is released, of course NOx stored as nitrate unstable more than sulfate is also released from the storage portion 44. - When the result at
step 201 is negative, the routine is finished. On the other hand, when the result atstep 201 is positive, atstep 202, the elapsed time (t) is reset to 0 as explained in the flow chart inFig. 3 . Next, atstep 203, it is determined if the elapsed time (t) reaches a set period (ts). The determination is repeated until the result is positive. When the result atstep 203 is positive, atstep 204, an amount of NOx stored in the storage portion 44 (A) during the set period (ts) is detected to make the air-fuel ratio of the exhaust gas rich as mentioned above. - Next, at
step 205, it is determined if the amount of stored NOx detected at this time (A) is equal to about the amount of stored NOx detected at the last time (A'). At first, the amount of stored NOx detected at the last time (A') is 0 and thus the result atstep 205 is negative. Therefore, the routine goes to step 206. - At
step 206, the amount of stored NOx detected at this time (A) is made the amount of stored NOx detected at the last time (A'). Next, atstep 207, the set period (ts) mentioned above is increased by (a) and the routine returns step 202. - When such processes are repeated, the set period (ts) is gradually lengthened and thus the amount of NOx stored in the storage portion 44 during the set period (ts) is gradually increased. Finally, the current amount of NOx that can be stored in the storage portion 44 is stored. Therefore, at next time, the amount of stored NOx detected at this time (A) is equal to about the amount of stored NOx detected at the last time (A'), the result at
step 205 is positive, and the routine goes to step 208. Thus, the current amount of NOx that can be stored in the storage portion 44 can be detected accurately at a short time. - The amount of NOx stored in the storage portion 44 (A) detected in this way is the amount of NOx that can be stored when the storage portion 44 is exposed only during a short period (a few minutes or a few ten minutes) after all NOx and SOx stored in the storage portion 44 have been released and becomes the current amount of NOx that can be stored in the storage portion 44 (B) when SOx is not stored because SOx is not almost stored in the storage portion 44 during such a short period. Accordingly, at
step 208, the amount of stored NOx detected at this time (A) is made the current amount of NOx that can be stored (B) in the storage portion 44 when SOx is not stored. Next, atstep 209, the amount of stored NOx detected at the last time (A') is reset to 0 and the routine is finished. - Thus, the current amount of NOx that can be stored in the storage portion 44 (B) when SOx is not stored is updated as the standard, and can be used in the estimation of the amount of SOx stored in the storage portion 44 (B-A) at
step 105 of the flow chart inFig. 3 . - In the flow charts of
Figs. 3 and5 , the elapsed time (t) for storing NOx in the storage portion 44 can be changed to a running distance. The air-fuel ratio of the exhaust gas is made rich to detect the amount of NOx stored in the storage portion 44 (A). This does not limit to the present invention. For example, even if the oxygen concentration is not dropped, NOx stored in the storage portion 44 is released when the temperature of the storage portion becomes about 500 degrees C. Accordingly, with utilizing this, theelectric heater 43 heats the storage portion 44 and the amount of NOx stored in the storage portion 44 (A) may be detected on the basis of a quantity of heat used to release all amount of NOx from the storage portion 44. - When the air-fuel ratio of the exhaust gas is made rich in the regeneration treatment of the NOx
catalyst device 2 and the detection of the amount of NOx stored in the storage portion 44, the air-fuel ratio of combustion in the engine may be made rich, additional fuel may be supplied into cylinder in exhaust stroke or expansion stroke, or fuel may be supplied to the exhaust gas in theexhaust passage 1. -
- 1:
- exhaust passage
- 2:
- NOx catalyst device
- 3:
- S trap device
- 4:
- detector for detecting sulfur components
- 42:
- temperature sensor
- 43:
- electric heater
- 44:
- storage portion
Claims (5)
- A detector for detecting sulfur components comprising a storage portion for storing SOx and NOx in the exhaust gas passing through an exhaust passage, in which the more an amount of stored SOx increases, the more an amount of NOx that can be stored decreases, estimating said amount of stored SOx on the basis of an amount of NOx stored in said storage portion, and detecting an integrated amount of SOx passing through the exhaust passage during a given period or an value on the basis of said integrated amount, characterized in that the estimating of said amount of stored SOx for detecting said integrated amount of SOx or said value on the basis of said integrated amount is prohibited when a current amount of NOx that can be stored is not stored in said storage portion.
- A detector for detecting sulfur components according to claim 1 characterized in that the estimating of said amount of stored SOx for detecting said integrated amount of SOx or said value on the basis of said integrated amount is prohibited when a temperature of said storage portion is out of a set temperature range.
- A detector for detecting sulfur components according to claim 2 characterized in that said set temperature range includes a temperature at which a current amount of NOx that can be stored in said storage portion is maximized.
- A detector for detecting sulfur components according to claim 1 characterized in that after all NOx and SOx stored in said storage portion are released, an amount of NOx stored in said storage portion during a set period is detected by releasing all said amount of stored NOx, when said set period is gradually lengthened, each amount of NOx stored in said storage portion during each set period is detected, a maximum value of the detected amounts of stored NOx is set to a current amount of NOx that can be stored in said storage portion when SOx is not stored.
- A detector for detecting sulfur components according to any one of claims 1-4 characterized in that said storage portion stores NOx in exhaust gas as nitrate and oxygen is supplied in the vicinity of said storage portion.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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PCT/JP2009/070934 WO2011070687A1 (en) | 2009-12-09 | 2009-12-09 | Device for detecting sulfur component |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2511697A1 true EP2511697A1 (en) | 2012-10-17 |
EP2511697A4 EP2511697A4 (en) | 2016-11-02 |
Family
ID=44145256
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP09852083.6A Withdrawn EP2511697A4 (en) | 2009-12-09 | 2009-12-09 | Device for detecting sulfur component |
Country Status (5)
Country | Link |
---|---|
US (1) | US8695399B2 (en) |
EP (1) | EP2511697A4 (en) |
JP (1) | JP5477381B2 (en) |
CN (1) | CN102667460B (en) |
WO (1) | WO2011070687A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2570801A1 (en) * | 2010-05-12 | 2013-03-20 | Toyota Jidosha Kabushiki Kaisha | Device for detecting sulfur component |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015004846A1 (en) * | 2013-07-12 | 2015-01-15 | Toyota Jidosha Kabushiki Kaisha | SOx CONCENTRATION DETECTION DEVICE OF INTERNAL COMBUSTION ENGINE |
JP6235270B2 (en) * | 2013-08-23 | 2017-11-22 | 株式会社Soken | Control device and control method for internal combustion engine |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4186176A (en) * | 1977-08-04 | 1980-01-29 | Asahi Kasei Kogyo Kabushiki Kaisha | Method of simultaneously removing sulfur dioxide and nitrogen oxides from exhaust gases |
US5397708A (en) * | 1993-05-13 | 1995-03-14 | Nalco Chemical Company | Method for detection of sulfides |
EP0944428B1 (en) * | 1996-08-19 | 2013-06-26 | Volkswagen Aktiengesellschaft | Method for operating an internal combustion engine with a NOx adsorber |
JP2001003735A (en) * | 1999-06-18 | 2001-01-09 | Hitachi Ltd | Engine exhaust emission control device |
JP2004092431A (en) | 2002-08-29 | 2004-03-25 | Toyota Motor Corp | Emission control device |
JP5012036B2 (en) * | 2007-01-17 | 2012-08-29 | トヨタ自動車株式会社 | Sulfur component detector |
-
2009
- 2009-12-09 US US13/255,009 patent/US8695399B2/en not_active Expired - Fee Related
- 2009-12-09 EP EP09852083.6A patent/EP2511697A4/en not_active Withdrawn
- 2009-12-09 WO PCT/JP2009/070934 patent/WO2011070687A1/en active Application Filing
- 2009-12-09 JP JP2011514917A patent/JP5477381B2/en not_active Expired - Fee Related
- 2009-12-09 CN CN200980162792.XA patent/CN102667460B/en not_active Expired - Fee Related
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2570801A1 (en) * | 2010-05-12 | 2013-03-20 | Toyota Jidosha Kabushiki Kaisha | Device for detecting sulfur component |
EP2570801A4 (en) * | 2010-05-12 | 2013-10-23 | Toyota Motor Co Ltd | Device for detecting sulfur component |
Also Published As
Publication number | Publication date |
---|---|
US8695399B2 (en) | 2014-04-15 |
WO2011070687A1 (en) | 2011-06-16 |
CN102667460B (en) | 2014-09-03 |
JPWO2011070687A1 (en) | 2013-04-22 |
JP5477381B2 (en) | 2014-04-23 |
CN102667460A (en) | 2012-09-12 |
EP2511697A4 (en) | 2016-11-02 |
US20120279278A1 (en) | 2012-11-08 |
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